Athletic shoes for use in various athletic activities, such as running, training, basketball, soccer, football and the like, have been constructed with uppers made of various materials. For example athletic shoe uppers have been constructed entirely of leather, entirely of synthetic materials or of a combination of leather and synthetic materials.
Where the athletic activity for which the shoe is used is primarily running, synthetic uppers are generally preferred because they are light and maintain their properties of comfort and softness regardless of exposure to moisture. However, synthetic uppers either do not stretch, or the synthetic uppers "give," that is move rather than stretch, in certain directions without forming to the foot. For example, oxford nylon does not stretch, while certain synthetic meshes stretch and/or move along their bias without forming to the foot. An example of a multi-layered synthetic upper is illustrated in U.S. Pat. No. 3,583,081 to Hayashi. The inner layer of material in the Hayashi upper is a woven or knit synthetic or natural fiber having higher elasticity as compared with the material of the outer layer. An intermediate layer of a resilient porous synthetic resin rubber or natural fiber is placed between the inner and outer layers.
When athletic shoe uppers are constructed entirely of leather, a balance has to be struck between the length of durability of the upper and its weight. In athletic endeavors, wherein the weight of the shoe is not critical but its strength or durability are, the leather upper has been made of relatively thick and heavy leather. Athletic shoes utilizing relatively thick leather generally take advantage of the capability of the leather to stretch and, hence, to mold or conform to the shape of the particular users foot. When relatively thick leather is utilized, or when the activity in which the shoe is used is not strenuous, the leather generally will not stretch to an extreme degree where the shoe becomes out of shape or ill fitting.
In certain athletic endeavors, for example running, in particular competitive running, the weight of the shoe becomes an important criteria. Relatively thin fine leather thus has been used in racing uppers. The stretching capability of the leather allows the upper material to mold itself to the form of the particular users foot. However, when such relatively thin leather is used, the stretching is unabated and the upper can eventually stretch out of shape. U.S. Pat. No. Re. 23,922 to Shapiro is an example of a track shoe having an all leather upper of kidskin and of an attempt to alleviate the stretching problem. A band of relatively nonstretching material is attached along the length of the leather upper to control stretching of the kidskin in the longitudinal direction. The relatively nonstretchable material does not cover the entire toe section, but rather extends as a band of less width than the upper from the toe of the upper to the heel of the upper. Thus, the strip of nonstretching material is intended to alleviate stretching primarily in the longitudinal direction.
Athletic shoe uppers have also been constructed of a combination of materials, for example, an upper with a toe section made of leather and a heel section of a synthetic woven fabric, such as nylon. An example of such an upper construction is found in U.S. Pat. No. 3,822,488 to Johnson.
Another example of a prior art upper constructed of various materials is found in U.S. Pat. No. 4,255,876 to Johnson. The upper in the '876 patent includes a toe section, which is multi-layered and stretchable, and a main body section, which is also multi-layered but nonstretchable.
Numerous current commercial running shoes have uppers with toe sections (sections forward of the metatarsal heads), which are stretchable and are formed of a combination of materials, and with a main body section rearward of the toe section, which is non-stretchable. The materials in the toe section typically are leather and a three layer laminate including an inner layer synthetic liner, a middle cushioning layer of synthetic foam, and an outer layer of synthetic multifilament mesh which stretches in all directions. Such a toe section is typically attached to the main body section formed primarily of a tight woven, nonstretchable synthetic material.